cutils: Add support for reading a processes scheduler policy (c0dfca7a) · Commits · e / os / android_system_core

include/cutils/sched_policy.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -27,6 +27,7 @@ typedef enum {
		} SchedPolicy;

		extern int set_sched_policy(int tid, SchedPolicy policy);
		extern int get_sched_policy(int tid, SchedPolicy *policy);

		#ifdef __cplusplus
		}

libcutils/sched_policy.c

+88 −3

Original line number	Diff line number	Diff line
		@@ -37,6 +37,8 @@
		#define SCHED_BATCH 3
		#endif

		static int __sys_supports_schedgroups = -1;

		static int add_tid_to_cgroup(int tid, const char *grp_name)
		{
		int fd;
		@@ -58,10 +60,8 @@ static int add_tid_to_cgroup(int tid, const char *grp_name)
		return 0;
		}

		int set_sched_policy(int tid, SchedPolicy policy)
		static inline void initialize()
		{
		static int __sys_supports_schedgroups = -1;

		if (__sys_supports_schedgroups < 0) {
		if (!access("/dev/cpuctl/tasks", F_OK)) {
		__sys_supports_schedgroups = 1;
		@@ -69,6 +69,91 @@ int set_sched_policy(int tid, SchedPolicy policy)
		__sys_supports_schedgroups = 0;
		}
		}
		}

		/*
		* Try to get the scheduler group.
		*
		* The data from /proc/<pid>/cgroup looks like:
		* 2:cpu:/bg_non_interactive
		*
		* We return the part after the "/", which will be an empty string for
		* the default cgroup. If the string is longer than "bufLen", the string
		* will be truncated.
		*/
		static int getSchedulerGroup(int tid, char* buf, size_t bufLen)
		{
		#ifdef HAVE_ANDROID_OS
		char pathBuf[32];
		char readBuf[256];
		ssize_t count;
		int fd;

		snprintf(pathBuf, sizeof(pathBuf), "/proc/%d/cgroup", tid);
		if ((fd = open(pathBuf, O_RDONLY)) < 0) {
		return -1;
		}

		count = read(fd, readBuf, sizeof(readBuf));
		if (count <= 0) {
		close(fd);
		errno = ENODATA;
		return -1;
		}
		close(fd);

		readBuf[--count] = '\0'; /* remove the '\n', now count==strlen */

		char* cp = strchr(readBuf, '/');
		if (cp == NULL) {
		readBuf[sizeof(readBuf)-1] = '\0';
		errno = ENODATA;
		return -1;
		}

		memcpy(buf, cp+1, count); /* count-1 for cp+1, count+1 for NUL */
		return 0;
		#else
		errno = ENOSYS;
		return -1;
		#endif
		}

		int get_sched_policy(int tid, SchedPolicy *policy)
		{
		initialize();

		if (__sys_supports_schedgroups) {
		char grpBuf[32];
		if (getSchedulerGroup(tid, grpBuf, sizeof(grpBuf)) < 0)
		return -1;
		if (grpBuf[0] == '\0') {
		*policy = SP_FOREGROUND;
		} else if (!strcmp(grpBuf, "bg_non_interactive")) {
		*policy = SP_BACKGROUND;
		} else {
		errno = ERANGE;
		return -1;
		}
		} else {
		int rc = sched_getscheduler(tid);
		if (rc < 0)
		return -1;
		else if (rc == SCHED_NORMAL)
		*policy = SP_FOREGROUND;
		else if (rc == SCHED_BATCH)
		*policy = SP_BACKGROUND;
		else {
		errno = ERANGE;
		return -1;
		}
		}
		return 0;
		}

		int set_sched_policy(int tid, SchedPolicy policy)
		{
		initialize();

		if (__sys_supports_schedgroups) {
		const char *grp = NULL;